Jaekelopterus (Yay-kel-op-ter-us) - one of the largest arthropods to have ever lived. An incomplete claw fossil, part of an enormous pair of grasping pincers that were located in front of the mouth, measures over 36 cm in length. Based on this material, scientists have estimated that this Early Devonian invertebrate measured around 2.6 metres in length. Its fossils come from Germany and although these animals are known as “sea scorpions” (eurypterids), Jaekelopterus lived in freshwater and estuaries. It was an active hunter and there are fossils of early fish with puncture wounds probably caused by its massive pincers.